Frequency synthesizers are utilized in a variety of electronic circuits, including test equipment and the like, wherein it is necessary to provide any of a wide range of frequencies. Generally the frequencies are provided in small steps over the entire range and may be provided by sweeping through the range a step at a time or moving directly to a desired step frequency.
Prior art frequency synthesizers are described in U.S. Pat. Nos. 3,696,906, entitled "Coherent Jump Frequency Synthesizer", issued Oct. 3, 1972, and 4,001,714, entitled "Search and Confirm Frequency Synthesizer", issued Jan. 4, 1977, both of which are assigned to the same assignee. Both of the above disclosed frequency synthesizers are less versatile and require much more complicated circuitry than the present frequency synthesizer.